The cost of Candy Bar A is displayed in the table. The proportional relationship between the cost and quantity for Candy Bar B is represented by the equation y = x. Which candy bar is the cheapest cost per bar?

1 = 1.25
2 = 2.50
3 = 3.75
4 = 5.00
5 = 6.25

Candy Bar B is the cheapest cost per bar. Since the equation for Candy Bar B is y = x, the cost is directly proportional to the quantity. This means that the cost per bar remains the same regardless of the quantity purchased. In this case, Candy Bar B costs $1 per bar, making it the cheapest option.